Reducing Mutual Coupling in Circular Motion-Based DOA Estimation: An Iterative Array Configuration Method

Mutual coupling (MC) has a severe effect on the direction-of-arrival (DOA) estimation and even leads to estimation failures. The emerging array motion techniques, which construct flexible virtual arrays with larger apertures by moving an initial array and combining phase-corrected signals sampled at designed time delays, have shown potential in mitigating the effect of MC by constructing virtual sensors. However, the virtual array remains susceptible to MC. To handle this problem, in this letter, a general synthetic signal model with MC is derived and an iterative method on the array configuration is proposed to form a virtual array with less MC for the circular motion-based DOA estimation. Specifically, a virtual uniform concentric circular array (VUCCA) is constructed by synthesizing all the observations at different time delays with uniform spacing, and the equation between MC matrix of the VUCCA and the initial array is derived, proving that the MC of VUCCA is solely related to the configuration of initial array. Thus, an iterative method is proposed to yield an optimal configuration with less MC by minimizing the norm close with MC. A higher degree-of-freedom and better estimation accuracy are achieved effectively.